3573 replies to this topic

[Bill from NH]

John, the small early Champion & Mura endbell bushings were oilite. If the Russkit endbell bushings are brass, so must have been the blind can bushings. You used to see these blind bushings soldered to the cans so they didn't come loose.

[havlicek]

If the Russkit endbell bushings are brass, so must have been the blind can bushings

Sure thing Bill. I have to look at them again sometime (the above "22" is" already packaged up to send out), but I'm fairly sure both are regular brass (the color is wrong to be bronze which is a better bushing material...but maybe???). Truthfully, I think good bushings are just as good or maybe even better in many cases than even good bearings. Bronze (whatever particular alloy is used for bushings) has excellent natural lubricity and wear resistance...it's not prone to galling.

You used to see these blind bushings soldered to the cans so they didn't come loose.

Yeah, I've seen more than one where the blind bushing is spinning in the can. I imagine that "bit" more than a few racers before they probably started soldering them in ahead of time. Pretty much like it only took 100,000 melted endbells before Mura or Champion (or whoever it was) finally figured out that a better endbell would be something people would actually pay for...adios Mr. Mabuchi!

But you are correct, we didn't get hotter than a 110/32 to live.

Amazing looking back now Rocky that a #32 wind was considered...er...risky

-john

[idare2bdul]

"Amazing looking back now Rocky that a #32 wind was considered...er...risky "

Thats because we have serious magnets now. This is one of the reasons the mini ProSlot motrs get hot with X12's, they have magnets that are marginal for that wind.

[havlicek]

That comes later in the pecking order Mike. In keeping with the "weakest link" rule, the fact that the brushes were riding directly on the plastic...which was only slightly more heat resistant than candle wax was primary. There are "hotter" winds that could work with those godawful magnets but would have PDQ "chernobyl'd" the brushes...hence the "heatsinks" (!) of the FT16D. You're right though and it wasn't long before better magnets upped the ante. There's a Mura endbell that pretty well fits the Mabuchi FT16D can that still has the Mabuchi style heatsinks but in a much better material...as well as the Champion "orange-picker" and even the Champion "white" (Cycolac??? or something) endbell which seems at least a little better. Things seemed to have happened pretty fast back then...endbells got better, magnets got better, winds got hotter, tires got better, chassis got better and each time...everything else had to get better to catch up. It's almost a cool thing in retrospect that the Mabuchis were so bad because it forced people to always be looking for the next "upgrade". Like a kid's version of the space program.

-john

[Alchemist]

I was wondering about the weight difference between a stock motor weight and it's weight after being rewound. Since heavier gauge is employed with a rewind and also dependent upon the amount of turns I deduced that the rewound motor would most likely be heavier - perhaps not by much but heavier just the same. I was incorrect - but not completely!!

I weighed a couple of motors for comparison, no pinions or solder on them.

I took a stock JK Hawk motor and weighed it. It tips the scale at 21.3 grams. I then took the Hawk motor that Sir John rewound for me and it tipped the scale at 21.4 grams. Not much of an increase at all.

Then, I weighed a stock Mura Challenger II, weighed in at 28.4 grams. Sir John did a hot rewind on a Challenger II I sent him and it weighed less!!! It weighed 28.3 grams.

I presumed there would be much more of a weight difference, but from my little comparison there isn't.

Just thought I'd share my findings. Thank you.

Ernie

[Bill from NH]

Ernie, I'm assuming your differences in weight are mainly due to different amounts of epoxy. Your findings seems to indicate that the Hawk doesn't come with enough epoxy yet John used less wire & more epoxy. On the Challenger II, John used less wire and did a better epoxy job with less epoxy than Mura. Don't forget to take into account the material removed by the balance holes.

[Alchemist]

Hi Bill,

Thank you for offering these important "tidbits" of info - really great tech stuff!! At least to me it is - LOL!!

Thank you Bill!

Ernie

[havlicek]

Hi Ernie,

Bill did a great job of figuring out why there are any weight differences...and there's one more possibility, what actual arm I used. I don't always use the same arm that came from the motor and there is a noticeable difference between the weight of different blanks. Even though they're all steel, some are different alloys, but the weight difference is really because of the shape of the arm lams not the alloy steel that's used. I don't recall what I used for your motors, but I may not have used the original arms after stripping them.

-john

[Bill from NH]

The width of the lamination's web & shape of its crown can be very different & present different weights, as can the stack length. I still maintain the final test will still be out on the track. Just because a certain motor ought to go faster on paper doesn't mean it will.

[havlicek]

I agree Bill 100%. Also, there's the "driveability" factor. Even if a motor IS faster...that doesn't mean it will result in shorter lap times. Then there's the "grenade factor"...a faster motor, even one that DOES produce faster individual lap times may not last the race. Lotsa factors

-john

[Prof. Fate]

Hi

"heavier wire" isn't heavier in weight by volume, but "heavier guage" which is a weakness in communication.

When 110/32 was "risky" for 16ds, we were all using 36ds! THAT is why we were using those monsters. Back in 64, regularly people would point out that things like the Revell Lotus 24(25?myth?) were the only way to do a "modern F1", but on commerical tracks, Formula One was dominated by Vanwals and Lancias and other 50s F1s that had ROOM for a proper 36d! Before Arcos even!

When the 26d came out, the 16ds still didn't have the parts to live with hot winds, and the 26d with a 65/30 wind STOCK was a wonder. But within a few months, we had hemi magnets and better endbells putting down the 36ds and 26ds.

Fate

[Alchemist]

I don't always use the same arm that came from the motor

Hi John,

I presumed you used the original arms and stack - but you probably mentioned that you replaced the arm and I didn't catch that part - LOL!!

Thank you.

Ernie

[havlicek]

I'm not sure Ernie...sometimes I replace the arm and sometimes I use it. I can get good results with modern arm blanks, but I have my doubts they ALL use the best "electrical steel" or "lamination steel" since it costs more (less carbon, some silicon). I would bet that the some older arms used better steel, but have no way of knowing for sure. In any case, I seem to get better results from certain arm blanks...not huge, but noticeable on average and that can be because of either the type of steel alloy used to form the laminations as well as the actual shape of the laminations themselves. The "science guys" might be able to fill in more of the info I always assumed that all motor manufacturers would just naturally only use good lamination steel, I'm not so sure now.

Rocky's right too about "heavier wire", the term meaning thicker in section or gauge. You could actually produce a heavier (*by weight) arm by using "lighter gauge wire since there would be less airspace in the coil...allowing more total copper, and copper is a relatively dense/heavy metal.

-john

[Alchemist]

Hi John, everyone!

What dictates the voltage (minimum/maximum) that the motor is capable of running on, especially after a rewind please?

The reason I ask is that my nephew showed me a few of his motors from his RC cars called Xmod and Mini Z. The motors look similar to Falcon/TSR/Hawk motors in size but he tells me that they run on battery packs that are less than 12 volts; something like 8 volts maximum on a battery pack. He mentioned that any more voltage would cause the motor to fail.

Is there any reason why these motors would not work on a slot car and vice versa.

I'd like to hear perspectives on this please.

Thank you.

Ernie

[havlicek]

Hi Ernie,

It's very simple actually...the more voltage the shorter the life. You can run motors that were made to "live" a fairly good life at 12V on 36V for short bursts and they may hold up fine. Say you have a motor that would normally live for 4 hours of track time at 12V, if you run that motor on 13+V it may only last for 2 1/2 hours. Your nephew's "8V" motors could probably do fine at 12V for a short period of time, they just wouldn't last very long. A rewind is no more apt to fail because of voltage than any other motor...it's just that not many people will rewind a motor to run slower than it did stock You may have seen people here from time to time laugh about old motor designations like "12V" or "6V" and it's just because of this...there are no standards.

This leads to another sort of related subject, that being that tracks often run at higher voltages...I guess to make the motors run faster and to add a little more excitement. However, this will shorten the life of the motors and in any case, as long as everyone runs at the same voltage, the racing will still be fair at lower voltages (12V nominal). If the motors being run aren't fast enough at 12V, you could just run motors that ARE fast enough at 12V. So I don't quite get why this is done...but I don't race so I'm probably missing something here.

-john

[GearBear]

John,

I think it is more than that. I believe the 8v motors in the Atomic/RC cars are wound with less turns of smaller wire. This makes the motor faster with less amp draw due to the small diameter of the arm wire. But once you put more amps and voltage on the motor it blows up because the small diameter wire can't handle the amperage (been there, done that). The RC guys have to worry about current draw much more than we do. They play the game of how hot they can wind the car and still have battery power at the end of their race. We don't have to worry about amp draw on our motors as we simply take everything we can get. So our hot arms are wound with hotter winds with larger wire in general. I'm sure TonyP can correct me if I'm wrong!

[havlicek]

Sure thing Gary. With a limited power source ...when the battery runs out...the car she's a no move-a The rule still applies though, as what you've described only matters as far as motor efficiency...lower amp draw means longer run time. As for volts (not current), a given DC motor will still last longer at a lower voltage and shorter at a higher voltage. Of course, if you take that "8V" motor and run it at 24V it's lifetime may only be a blip. If you run it at 3V, it will last longer on average than the same motor run at it's nominal operating voltage of 8V. That's why the drag guys would run nominal 6V motors at high voltages (24? 36?) for very short periods of time and get away with it.

-john

[havlicek]

I finished off an arm for another "Strapnut" I'm planning. Same .330" stack length, .014" lams of an unknown origin but this time I used on of Bill Bugenis' great coms, reason being...I did a #24 just to see what happens I was also extra careful with tieing and epoxying this one, leaving a little extra epoxy up near the com, figuring that's where it might be needed. I'm definitely going to send this one to Bill for dynamic balancing also, which is why it's not drilled yet. This one should definitely "dim the lights in Fresno", even if it's run on the East Coast!



This is sort of like the eurosport arms, except for the arm diameter and the wire gauge. It even might work in a eurosport setup if the OD was ground down appropriately...although I don't know that the wind is at all appropriate. I'm hoping that the neos will be up to this thing, but if not...it should make a dandy itty bitty drag arm. I've also been experimenting with refining the brazing process and have made some interesting progress in that area. Little by little...wax on...wax off.

-john

[Alchemist]

Hi John,

It's exciting to see the different - if I may say "experimental" rewinds! Are your "strapnuts" that much more powerful than the "walnuts" please?

Thank you.

Ernie

[havlicek]

Hi Ernie,

Are your "strapnuts" that much more powerful than the "walnuts" please?

...depends on the wind, but generally as... or more powerful at an even lighter weight. The arm above should be an "upper limit" (or beyond) motor when done. The only problem is that the danged neos suck up little bits of steel from all over my zipcode. I keep cleaning off my workbench surface (glass) and ten minutes later there's all kinds of stuff clinging to the motors. I never had that problem with Mabuchis

-john

[Victor Poulin]

Hi Ernie,



...depends on the wind, but generally as... or more powerful at an even lighter weight. The arm above should be an "upper limit" (or beyond) motor when done. The only problem is that the danged neos suck up little bits of steel from all over my zipcode. I keep cleaning off my workbench surface (glass) and ten minutes later there's all kinds of stuff clinging to the motors. I never had that problem with Mabuchis

-john

LOL John,

I have that problem even with reg ceramic motors, and I keep my bench pretty clean. All this time I thought it was just me

[Robert V.]

Hi guys

It's not just you guys i am working on a high performance 13d rebuild i used TSR magnets and i made the mistake of glueing them in with epoxy before i cut the can down i had to use duct tape to remove most of the metal dust from the can that was 3 days ago and i am still finding little bits of metal stuck to the can.

[havlicek]

What about honing magnets Robert. I have a slick Mura B motor with a full-on arm that needs the magnets/airgap honed out a little. I'm pretty sure that magnet putty would be mandatory to get all that fine dust out of there. I've never done it, but it sounds like a part time job for summer vacation

-john

[Victor Poulin]

Hey guys,
FWW- I have an air compressor that puts out 120 psi. I use a needle air blower at full boar, and it cleans every bit of that crap out of the can and magnets.

Just make darn sure your magnets are glued in real good !! Been there, done that !
I also do this just prior to installing the arm.

Vic

[Robert V.]

Yes magnet put sounds like it may work i will look for a substitute maybe silly putty, i wish my air compressor went that high i just use mine for airbrush work. Oh and as always the arm looks great pretty soon the comms you use will be as big as the stacks.